The present invention relates to data protocols, and in particular command protocols for model trains.
A variety of control systems are used to control model trains. In one system, the power to the track is increased, or decreased, to control the speed and direction of the train. Multiple trains can be controlled by providing different power levels to the different sections of the track having different trains.
In another type of control system, a coded signal is sent along the track, and addressed to the desired train, giving it a speed and direction. The train itself controls its speed by converting the AC voltage on the track into the desired DC motor voltage for the train according to the received instructions. The instructions can also tell the train to turn on or off its lights, horns, etc. U.S. Pat. Nos. 5,441,223 and 5,749,547 issued to Neil Young et al. show such a system.
FIG. 1A is a perspective drawing of an example layout of a conventional model train system allowing the communication of signals from a base unit to a locomotive and other components.
A hand-held remote control unit 12 is used to transmit signals to a base unit 14 and to a power master unit 150 both of which are connected to train tracks 16. Base unit 14 receives power through an AC adapter 18. A separate transformer 20 is connected to track 16 to apply power to the tracks through power master unit 150. Power master unit 150 is used to control the delivery of power to the track 16 and also is used to superimpose DC control signals on the AC power signal upon request by command signals from the hand-held remote control unit 12.
Power master unit 150 modulates AC track power to the track 16 and also superimposes DC control signals on the track to control special effects and locomotive 24′. Locomotive 24′ is, e.g., a standard Lionel locomotive powered by AC track power and receptive to DC control signals for, e.g., sound effects.
455 kHz transmitter 33 of base unit 14 is configured to transmit an outgoing RF signal between the track and earth ground, which generates an electromagnetic field indicated by lines 22 which propagates along the track. This field will pass through a locomotive 24 and will be received by a capacity antenna located inside the locomotive.
FIG. 1B is a simplified schematic drawing of the conventional system shown in FIG. 1A. FIG. 1B shows a cross-sectional view of locomotive 24, which may be, e.g., a standard locomotive retrofitted or designed to carry antenna 26. The signal will then be communicated from antenna 26 to 455 kHz receiver 37 of engine 24. Locomotive 26 further includes a processor 84 in communication with receiver 37 and configured to interpret the received signal.
Returning to FIG. 1A, receipt of control signals is not limited to moving elements of the train set. The electromagnetic field generated by base unit 14 will also propagate along a line 28 to a switch controller 30. Switch controller 30 also has a receiver in it, and will itself transmit control signals to various devices, such as the track switching module 32 or a moving flag 34.
The use of both base unit 14 and power master unit 150 allows operation and control of several types of locomotives on a single track layout. Locomotives 24 which have been retrofitted or designed to carry receiver 26 are receptive to control signals delivered via base unit 14. Standard locomotives 24′ which have not been so retrofitted may be controlled using DC offset signals produced by power master unit 150.
The remote unit can transmit commands wirelessly to base unit 14, power master unit 150, accessories such as accessory 31, and could transmit directly to train engines instead of through the tracks. Such a transmission directly to the train engine could be used for newer engines with a wireless receiver, while older train engines would continue to receive commands through the tracks. An example of a remote control is described in copending application Ser. No. 10/986,459, now U.S. Pat. No. 7,221,113.
The communication of signals to moveable and stationary components of a model train as described above, offers a number of advantages. Furthermore, even more advantages would be conferred by the ability to send and receive signals to specific train set components or cars configured to perform certain functions mimicking realistic actions of a train.
A railroad communication system is disclosed in U.S. Pat. No. 4,582,280. A radio communication control system allows for a lead unit to communicate with a plurality of remote units. The radio communication channel between the lead unit and the remote units also signals responses by the remote units to the commands from the lead unit. A functional radio communications link between a lead unit and a remote unit is not established until unique addressing information has been exchanged between the lead unit and the remote unit and comparisons have been made.
U.S. Pat. No. 5,831,348, discloses a wireless transmit-receive system including a power induction coil. The system allows for transmission of a power signal in a non-contact form according to mutual induction by using an induced electromotive force generated in a coil with a magnetic field. In this wireless transmit-receive system, a typical frequency used in a low-cost electromagnetic induction system is in a range from around 100 kHz to 1 MHz.
Examples of desired signals to be sent and received to the train cars are described in U.S. Pat. No. 3,664,060 issued to Longnecker. Simulated bell sounds, whistles, and steam blow-off sounds are examples of realistic locomotive sounds to be used in model train systems. Other signals include the control of couplers which link two cars together. It is an object to send these signals to specific cars based on their order or location in a train.
U.S. Pat. No. 5,777,547, discloses a car identification and ordering system for trains which identifies each car in the train, the order of the cars, the total number of cars, and the identification of the last car in the train. A master controller sends an identification request signal to the first car. Only the first car receives this signal because the repeater on the first car is temporarily disabled, and therefore the message is not transferred to the second car or any of the successive cars in the train. The car controller on the first car responds to this signal by sending an identification signal back to the master controller which provides the master controller with information regarding the first car. The master controller stores this car identification information into the first car position in its database or list. Then, the car controller re-enables the repeater on the first car to re-establish communication between the first car and the second car. This identification process is repeated down the line of cars in a train until the last car is identified. The system will know exactly how many cars are in the train and will have the order of the cars in its database or list.
Other examples of communication systems include K-Line's unidirectional communication from remote to train and Lionel's unidirectional link between the Engine and an Engine Tender.
It is an object of the invention, however, to provide a simple model train addressing system where commands are sent to desired train set components, without disabling the communication link between the cars.